Is it true that you lose most body heat from your head?

"You can lose 4045% of body heat from an unprotected head. That's the advice in a 1970s US Army Survival Manual, which is probably where this myth originated, says John Tregoning, a professor of vaccine immunology at Imperial College London. The reality is that there is nothing special about your head. When you go out in the cold, you lose more body heat from any area you leave exposed than from those parts protected by clothing."

"Nevertheless, there remains some discussion about whether the head is more susceptible to heat loss. Tregoning points to a British Medical Journal article from 2008 which suggests that because you've got less fat on your head than the rest of your body, it is slightly less naturally insulated. The article also argues that vasoconstriction the narrowing of blood vessels to conserve heat is less effective on the head. Overall, though, Tregoning says, the head does lose heat, but it's not uniquely heat-losing."

Wearing a hat reduces heat loss from an exposed head, but the head is not uniquely responsible for most body heat loss. Heat escapes from any uncovered body area, and larger exposed surface area causes greater loss. In cold conditions, an uncovered face and head will lose heat quickly while well-clothed areas cool more slowly. Areas with less fat, such as the head, are slightly less insulated, and vasoconstriction may be less effective there, raising per-area heat loss. Experimental comparisons found head cooling rates similar to other parts. Covering exposed areas reduces overall heat loss.

Read at www.theguardian.com